Monday, April 21, 2014

Influence of (Al, Fe, Mg) Impurities on Triclinic Ca3SiO5: Interpretations from DFT Calculations

Jian Huang, Loredana Valenzano, Tajendra Vir Singh, Ravindra Pandey, and Gaurav Sant
Articles ASAP (As Soon As Publishable)
Publication Date (Web): April 11, 2014 (Article)
DOI: 10.1021/cg401647f

Crystal Growth and Design

Ca3SiO5 and its polymorphic representations are the dominant phase(s) present in ordinary portland cement (OPC). As environmental pressures bracket the production of OPC, there is increasing emphasis on designing newer, more efficient OPC chemistries. While minor impurities in the form of (Al, Fe, Mg) are long understood to have substantial influences on the structure and reactivity of the siliceous cementing phases, specific details at the atomistic level remain unclear. In this paper, we report the results of first-principles calculations performed at the density functional level of theory (DFT), on triclinic Ca3SiO5, a template phase of relevance to OPC doped with (Al, Fe, Mg) species. Focus is devoted toward understanding modifications induced in (a) the lattice and crystallographic parameters, (b) the mechanical properties, and (c) the electronic descriptors of the silicate. Special efforts are devoted to identify preferred atomic substitution sites and to rank the stability of different phases using thermochemical descriptors. The results suggest that the presence of (Al, Fe, Mg) impurities in the silicate lattice modifies charge localization and exchange, contributing a new means toward interpreting and steering cementing phase reactivity, by careful manipulations of their impurity distributions.

Wednesday, April 16, 2014

Welcome to the Valenzano's Research Group

The Valenzano's research group at ACS National Meeting in Dallas (TX), March 2014. From left to right: Dr. Kapil Adhikari (PhD, Postdoc), Mr. Andy Perla (senior undergrad student), Assistant Prof. Loredana Valenzano (PhD, Group Leader), Mr. Daniel Beegle (senior undergrad student), Mr. Gemechis Degaga (MS, PhD student), Mr. Michael Szatkowski (junior undergrad student), Miss Kathryn Weinand (senior undergrad student).

I am very proud to list the ACS oral presentations representing the major outcomes of my research group's effort in the last year:

  • Andrew PerlaMichael Szatkowski, Loredana Valenzano, Action of a Broad Spectrum Antiviral Medication against Human Herpes: a Quantum Chemical Investigation
  • Daniel Beegle, Kapil Adhikari, Loredana Valenzano, Assembling the Peptidoglycan Bacterial Cell Wall: a Stepwise Quantum Chemical Approach
  • Gemechis Degaga, Loredana Valenzano, Adsorption of Light Hydrocarbons in Metal-Organic Frameworks: Computational Study at Quantum Chemical Level
  • Kapil Adhikari, Kenneth Flurchick, Loredana Valenzano, Mimicking Thermal Effects on Bulk Properties of Molecular Crystal Polymorphs and Cleaving their Surfaces from First Principles
  • Jian Huang (UCLA), Loredana Valenzano, Gaurav Sant (UCLA), Influence of (Mg, Al, Fe) Impurities on triclinic Ca3SiO5: Interpretations from DFT Calculations